Popup message using java script alert

 Hi, 

  I am trying to get a pop message in my OAF page once I click on a button (save), I can see the popup message only if there is an exception in my page or if I keep my java script code in processRequest, could anyone please help me know if there is a way that we can achieve the popup message through processformrequest?

 

Note: I can see the popup message when I write the code in processformrequest only when there is an exception on the page, but normally when there is no exception then I cannot see any popup.